hmm well theres not much you can diagnose since it was dropped but worth a shot. either way backup any important files. i would try chkdsk since its free. western digital or seagate has a software on their site i dont know which hdd you have. try that. memtest 86+ is free which checks ram, but seems to me thats its hard drive. try to look in post before bios or disable quick boot to see if it passes smart.